Invasive surgical procedures require a surgeon to create an incision in the patient's skin 150 in order to access a surgical site within the patient's body where the surgery is performed. A tissue retractor can be used during the surgical procedure and, in particular, during minimally invasive surgical procedures to temporarily displace tissue and create a relatively small working channel to the surgical site. The working channel of minimally invasive surgical procedures is typically smaller than working channels of traditional open procedures. Such minimally invasive tissue retractors allow unobstructed or nearly unobstructed access to the target or surgical site while limiting the amount of dissection required to achieve exposure of the surgical site. These minimally invasive tissue retractors also typically reduce trauma to the skin 150 and surrounding tissue when compared to traditional open procedures. The retractor can be used, for example, to provide access to a spinal disc, a vertebra and/or vertebrae during spinal surgery.
Referring to FIGS. 1-2B, there are several common lumbar spinal surgical procedures where the patient is positioned in the prone position (FIG. 1) on an operating table 11. A direct posterior lumbar surgical approach to conduct fusion of vertebrae may be referred to as a Posterior Lumbar Interbody Fusion (“PLIF”). An incision for this approach is typically made directly over the patient's mid-line. The procedure is not typically considered a minimally invasive procedure. Soft tissue and muscle are separated and retracted to provide an access channel to the surgical site. In the PLIF approach, soft tissue retraction may be provided by a known manual retractor (Weitlander, Gelpi, Williams, etc.). The procedure may include boney decompression of the lamina and/or facets, removal of the intervertebral disc and preparation of the disc space for fusion. The surgeon often distracts the intervertebral disc so that a relatively large or tall interbody implant or spacer may be inserted between the vertebral bodies, thereby promoting fusion. The surgeon may elect to distract the intervertebral disc space in an effort to restore disc height and sagittal balance. The distraction is often conducted via lamina spreaders, pedicle screw distractors and/or intervertebral body disc spreaders. Subsequently, the interbody spacer may be inserted into the distracted disc space to maintain height while the fusion process occurs over a postoperative timeframe, typically three to nine (3-9) months.
Transforaminal Lumbar Interbody Fusion (“TLIF”) is an alternate approach to the PLIF procedure and may generally be conducted in a minimally invasive manner. The surgeon typically makes a single, unilateral surgical incision, approximately two to four centimeters (2-4 cm) lateral to the patient's midline. The approach trajectory is between the multifidus and longissimus muscles 21, 22 using a technique described by Wiltse, which ends at a facet capsule of the targeted vertebral level. The soft tissue and muscle along the surgical path is dissected and retracted to provide a working channel to the surgical site. All surgical work is typically conducted through this single, relatively small incision. Several specialized retractors and systems are available to establish and retain a working channel through the soft tissue. A minimally invasive TLIF approach, with the use of a specialized retraction system, has the potential to be a less traumatic procedure to the patient than the open PLIF procedure, resulting in quicker short-term recovery.
Extracavitary Lumbar Interbody Fusion (“ELIF”) is a posterior lumbar interbody fusion technique that approaches the posteriolateral disc from a highly oblique posterior trajectory. The surgeon typically makes a single, unilateral surgical incision about five to eight centimeters (5-8 cm) lateral to the patient's midline with the patient in the prone position (FIG. 1). The trajectory typically approaches the spine 12 between the longissimus and illiocostalis muscles 22, 23 passing through a “safe zone”, as described by Kambin (i.e., Kambin's triangle). The ELIF approach is typically considered a minimally invasive technique, similar to the TLIF approach. However, ELIF often presents additional approach challenges over the TLIF procedure.
Prior art retractors are able to create a working channel for the above-described PLIF, ELIF and TLIF procedures. When performing minimally invasive procedures like the TLIF or ELIF procedures, surgical exposure is sometimes limited by the retractor utilized for a procedure and such procedures can be difficult for surgeons to perform through the relatively small surgical channels that are created by such existing retractors. The surgeon typically requires insertion of a plurality of surgical instruments into the working channel to manipulate the surgical site. The surgeon also typically needs to perform secondary manipulative maneuvers of the spine and particular vertebrae, such as distraction or compression. The secondary maneuvers are typically done with separate instruments that may not be insertable through the working channel created by prior art retractors.
When used during a minimally invasive posterior lumbar spine procedure, a tissue retractor is typically inserted through an incision in the skin 150 that can be two to eight centimeters (2-8 cm) lateral from the patient's midline. The retractor is typically stabilized using a table mount arm system that secures the retractor to the operating table 11. The table mount requires additional equipment near the incision and takes-up extra space near the operating table 11. The table mount also requires additional time to set up and properly mount due to the position of the patient 10. The table mount can also clutter the surgical field by obstructing access to the incision. The table mount may also clutter fluoroscopy conducted at the surgical site by blocking and/or obstructing interoperative x-rays or other imaging techniques.
Surgical procedures conducted through a minimally invasive working channel for TLIF and ELIF procedures can be challenging due to space restrictions, confinement and limitations of prior art retractors. Existing retractors may also be limited to specific access angles to the surgical site. TLIF and ELIF procedures can also be complicated by prior art retractors and table mounts “cluttering” the surgical field. Retractor table mount hardware is often cumbersome, requires significant set-up and impedes visibility to the surgical site and through the working channel. Generally, a lateral-type approach incision, typical of ELIF procedures, amplifies the above challenges due to the larger instrument angulations and approach trajectories.
It would be desirable to design and implement a retractor that does not create or minimizes “clutter” in the working field to provide maximum site lines to the surgical site during minimally invasive procedures. It would also be desirable to design and construct a minimally invasive retractor that combines functionality for conducting additional procedures that are typical with ELIF and TLIF procedures, such as distraction of adjacent vertebrae. Further, it would be desirable to design and implement a retractor that is able to define a working channel in various access trajectories that are utilized by the surgeon. The present retractor generally addresses the described disadvantages of prior art retractors.